Article History
Received: 4 January 2019
Revised: 6 June 2019
Accepted: 29 July 2019
First Online: 8 August 2019
Compliance with ethical standards
:
: The authors declare that they have no conflicts of interest.
: Approval of the retrospective study was obtained from the research ethics committee of the First Affiliated Hospital of China Medical University.
: For this type of study, formal consent is not required.